﻿302 
  S. 
  B. 
  Kuzirian 
  — 
  Action 
  of 
  Sodium 
  Paratungstate. 
  

  

  halogen 
  salts. 
  The 
  reaction 
  proceeds 
  to 
  completion 
  without 
  

   any 
  difficulty, 
  and 
  this 
  flux 
  seems 
  to 
  be 
  capable 
  of 
  expelling 
  

   the 
  iodine 
  completely 
  from 
  iodides 
  in 
  a 
  gentle 
  ignition 
  of 
  from 
  

   five 
  to 
  ten 
  minutes. 
  

  

  In 
  the 
  case 
  of 
  fluorides, 
  chlorides, 
  and 
  bromides 
  it 
  appears 
  that 
  

   the 
  action 
  of 
  sodium 
  paratungstate 
  in 
  the 
  expulsion 
  of 
  the 
  hal- 
  

   ogen 
  element 
  from 
  chlorides 
  is 
  not 
  complete 
  for 
  the 
  reason 
  that 
  

   the 
  simple 
  elimination 
  of 
  that 
  element 
  will 
  not 
  leave 
  an 
  oxide 
  to 
  

   combine 
  with 
  the 
  acidic 
  oxide 
  of 
  the 
  flux. 
  If 
  the 
  fusion 
  with 
  

   the 
  flux 
  were 
  carried 
  in 
  vacuo 
  or 
  in 
  an 
  atmosphere 
  free 
  of 
  

   oxygen 
  there 
  would 
  probably 
  be 
  no 
  marked 
  decomposition. 
  

   So 
  the 
  observed 
  partial 
  decomposition 
  of 
  the 
  halogen 
  salts 
  with 
  

   a 
  slow 
  evolution 
  of 
  the 
  halogen 
  is 
  apparently 
  due 
  to 
  the 
  agency 
  

   of 
  atmospheric 
  oxygen, 
  or 
  moisture, 
  which 
  may 
  serve 
  essentially 
  

   the 
  end 
  of 
  oxidizing 
  the 
  metal 
  to 
  a 
  basic 
  oxide 
  which 
  combines 
  

   with 
  the 
  acidic 
  tungstic 
  oxide, 
  thus 
  helping 
  in 
  the 
  expulsion 
  of 
  

   the 
  halogen. 
  This 
  action, 
  which 
  may 
  be 
  represented 
  by 
  the 
  

   following 
  equation 
  : 
  

  

  28NaX 
  + 
  2(5Na 
  2 
  0.12W0 
  3 
  ) 
  + 
  70 
  2 
  = 
  24Na 
  2 
  W0 
  4 
  + 
  14X 
  2 
  

   14NaX 
  + 
  5 
  Na 
  2 
  0. 
  J 
  2 
  W0 
  3 
  + 
  7H 
  2 
  = 
  5Na 
  2 
  W0 
  4 
  + 
  7K 
  2 
  W0 
  4 
  + 
  14HX 
  

  

  is 
  slow 
  and 
  incomplete. 
  

  

  The 
  complete 
  decomposition 
  of 
  iodides 
  with 
  this 
  flux 
  can 
  be 
  

   accounted 
  for 
  by 
  the 
  higher 
  susceptibility 
  of 
  these 
  salts 
  to 
  

   atmospheric 
  action. 
  

  

  The 
  disappearance 
  of 
  the 
  beautiful 
  violet 
  color 
  of 
  iodine 
  

   is 
  a 
  fair 
  indication 
  of 
  the 
  completion 
  of 
  reaction. 
  A 
  wide- 
  

   bottomed 
  platinum 
  crucible 
  is 
  advantageous 
  in 
  these 
  determi- 
  

   nations, 
  on 
  account 
  of 
  the 
  large 
  surface 
  exposure 
  of 
  the 
  con- 
  

   tents 
  to 
  the 
  atmospheric 
  action. 
  It 
  is 
  also 
  desirable 
  to 
  shake 
  

   gently 
  the 
  contents 
  of 
  the 
  crucible 
  when 
  the 
  end 
  point 
  is 
  ap- 
  

   proached, 
  thus 
  giving 
  a 
  better 
  chance 
  for 
  oxidation. 
  The 
  

   use 
  of 
  sodium 
  paratungstate 
  in 
  the 
  estimation 
  of 
  iodine 
  in 
  

   iodides 
  is 
  shown 
  in 
  the 
  following 
  table 
  : 
  

  

  Analysis 
  of 
  C. 
  P. 
  KI 
  of 
  Commerce, 
  after 
  Drying. 
  

  

  

  KI 
  Na 
  10 
  W 
  12 
  O 
  4 
  

  

  i 
  Loss 
  on 
  

  

  Theory 
  

  

  

  

  taken 
  

  

  taken 
  

  

  ignition 
  

  

  for 
  loss 
  

  

  Error 
  

  

  Jo. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  1 
  

  

  0-3000 
  

  

  2* 
  

  

  0-2170 
  

  

  0-2149 
  

  

  + 
  0-0021 
  

  

  2 
  

  

  0-3000 
  

  

  2- 
  

  

  0-2155 
  

  

  0-2149 
  

  

  + 
  0-0006 
  

  

  3 
  

  

  0-3000 
  

  

  2- 
  

  

  0-2154 
  

  

  0-2149 
  

  

  + 
  0-0005 
  

  

  4 
  

  

  0-3000 
  

  

  2' 
  

  

  0-2156 
  

  

  0-2149 
  

  

  + 
  0-0007 
  

  

  5 
  

  

  0-3000 
  

  

  2- 
  

  

  0*2157 
  

  

  0-2149 
  

  

  + 
  0-0008 
  

  

  6 
  

  

  0-3000 
  

  

  2- 
  

  

  0-2148 
  

  

  0-2149 
  

  

  — 
  o-oooi 
  

  

  